A study of cartilage and bone induced in cortisonized mice by cultured human cancer cells. The mechanism of cartilage induction and the mechanism of cartilage calcification as mediated by ultramicroscopic matrix vesicles are being studied using techniques of electron microscopy, autoradiography, tissue culture and chemical analysis of calcium, phosphatase and proteoglycans. BIBLIOGRAPHIC REFERENCES: Anderson, H. C. and Brosnan, E. J. Bone formation in HeLa cell tumors explanted to mouse brain. In: Extracellular Matrix Influences on Gene Expression. H. C. Slavkin and R. C. Gruelich, editors. New York Academic Press. pp. 627-632, 1975. Anderson, H. C., Cecil, R. and Sajdera, S. W. Calcification of rachitic cartilage in vitro by extracellular matrix vesicles. Am. J. Path. 79: 237-254, 1975.